CN110000355B - Method for improving frame segregation of bloom continuous casting billet - Google Patents
Method for improving frame segregation of bloom continuous casting billet Download PDFInfo
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- CN110000355B CN110000355B CN201910299087.XA CN201910299087A CN110000355B CN 110000355 B CN110000355 B CN 110000355B CN 201910299087 A CN201910299087 A CN 201910299087A CN 110000355 B CN110000355 B CN 110000355B
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- continuous casting
- segregation
- electromagnetic stirring
- secondary cooling
- casting billet
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
Abstract
The invention discloses a method for improving frame segregation of a bloom continuous casting billet, which comprises the step of carrying out continuous casting production by adopting a continuous casting machine with the casting billet section size of 400-400 mm in width and 400-400 mm in thickness, wherein the casting speed of the continuous casting billet is 0.45-0.60 m/min; the specific water amount of the secondary cooling area is 0.20-0.30L/kg; the crystallizer is electromagnetically stirred and arranged 500mm below the molten steel surface, the current intensity is 150-; the secondary cooling electromagnetic stirring device is arranged below the molten steel surface at 5000-. The method effectively improves the frame segregation of the bloom continuous casting billet according to the technological parameter characteristics, the drawing speed, the electromagnetic stirring of the crystallizer, the secondary cooling electromagnetic stirring position and the like of the continuous casting machine.
Description
Technical Field
The invention relates to the field of billet continuous casting, in particular to a method for improving the frame segregation of a bloom continuous casting billet.
Background
In the continuous casting process, molten steel is rapidly cooled in a crystallizer, and an overcooling area with large temperature gradient is formed on the surface of a continuous casting billet to form fine isometric crystals. As the continuous casting billet is pulled out of the crystallizer, the temperature gradient of the molten steel in the solidified billet shell is gradually reduced to form columnar crystals, and then primary crystals and secondary crystals are formed, the primary crystals continue to drive inclusions and solutes to a liquid phase, and the secondary dendrite arms prevent the inclusions and the solutes from continuously flowing or diffusing to the liquid phase, so that numerous dendrite arms with less impurities and solutes are formed in the columnar crystal zone, and micro segregation is formed by more impurities and solutes among dendrites. And at the end of the formation of the columnar crystal, simultaneously forming the central equiaxed crystal, so that the solidification front of the columnar crystal and the solidification front of the central equiaxed crystal simultaneously push elements and impurities to the tail end of the columnar crystal and the junction of the columnar crystal and the central equiaxed crystal, and thus macro-segregation is formed, namely frame-type segregation along the tail end of the columnar crystal and the junction of the columnar crystal and the equiaxed crystal is formed.
The damage of the frame segregation defect of the continuous casting billet to the finished product is that the structure is not uniform or the carbide is not uniformly distributed in the cooling after rolling. The segregation causes the mechanical property of the steel to have directionality, causes uneven mechanical property and reduced hardenability of different areas inside and outside the frame belt, and can not be uniformly coordinated when stressed and deformed, thereby causing local stress concentration and easy generation of cracks, and causing deformation and cracking.
At present, a great deal of research is carried out on frame type segregation, but the technology related to controlling the frame type segregation of continuous casting billets and related patents are few, for example, patent No. CN201210174384.X discloses a method for reducing the frame type segregation of Cr and Mo steel rolling materials. Continuously casting Cr and Mo steel billets, and controlling the electromagnetic stirring intensity, frequency, total water quantity, specific water quantity, overheating and drawing speed of a secondary cooling area; then cogging is carried out, the heating temperature is 1220-; rolling, wherein the rough rolling temperature is 1080 ℃, the finish rolling temperature is 935 ℃, the spinning temperature is 860 ℃, after rolling, rapidly cooling to 530-480 ℃ at a cooling rate of more than 5 ℃/S, and keeping the temperature to about 300-; the Cr and Mo steel rolled material for eliminating the frame segregation has slight tissue unevenness, and the simplified annealing process for eliminating the tissue unevenness is carried out.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a method for improving the frame segregation of a bloom continuous casting billet, which can effectively improve the frame segregation of the bloom continuous casting billet.
The technical scheme is as follows: the method for improving the frame segregation of the bloom continuous casting billet comprises the step of carrying out continuous casting production by adopting a continuous casting machine, wherein the casting speed of the continuous casting billet is 0.45-0.60 m/min; the specific water amount of the secondary cooling area is 0.20-0.30L/kg; the electromagnetic stirring current intensity of the crystallizer is 150-350A, and the frequency is 1.0-2.5 Hz; the current intensity of the secondary cooling electromagnetic stirring is 500-1000A, and the frequency is 5-8 Hz.
Wherein the casting blank section size of the continuous casting machine is 400-500mm in width and 400-400 mm in thickness.
The crystallizer is arranged 500mm below the molten steel surface through electromagnetic stirring.
The secondary cooling electromagnetic stirring device is arranged below the molten steel surface by 5000-.
Has the advantages that: 1. according to the method, proper crystallizer electromagnetic stirring and secondary cooling electromagnetic stirring positions and crystallizer electromagnetic stirring and secondary cooling electromagnetic stirring parameters are selected according to continuous casting process parameters, continuous casting drawing speed and a secondary cooling system, so that the frame segregation of a bloom continuous casting blank is improved; 2. the frame segregation of the rolled material of Cr and Mo steel is eliminated, so that the frame segregation under cold acid reaches or approaches 0 level, and the frame segregation under hot acid is controlled to be less than or equal to 1.0 level.
Drawings
FIG. 1 is a schematic diagram of the position of a carbon content measurement point at a frame-type segregation site according to the present invention.
Detailed Description
Example 1
A method for improving frame segregation 1 of a bloom continuous casting blank adopts a continuous casting machine to carry out continuous casting production:
the carbon content of the steel grade is 0.20 percent (mass percentage content of C), the width of the continuous casting billet 2 is 400mm, the thickness of the continuous casting billet is 300mm, the drawing speed is 0.60m/min, and the specific water content of the secondary cooling area is 0.30L/kg; the crystallizer is electromagnetically stirred to be 500mm below the liquid level of the steel, the current intensity is 150A, and the frequency is 2.5 Hz; the secondary cooling electromagnetic stirring is positioned 5000mm below the liquid level of the steel, the current intensity is 150A, and the frequency is 2.5 Hz. Referring to fig. 1, the average value of the carbon content of 16 points at the position of frame type segregation 1 is taken to calculate the segregation index, and the carbon segregation index is reduced from 1.05 to 1.02 by adopting the parameter of the patent.
Example 2
A method for improving frame segregation 1 of a bloom continuous casting blank adopts a continuous casting machine to carry out continuous casting production:
wherein the carbon content of the steel is 0.95 percent (mass percentage content of C), the width of the continuous casting billet 2 is 500mm, the thickness of the continuous casting billet is 400mm, the drawing speed is 0.45m/min, and the specific water content of the secondary cooling area is 0.20L/kg; the crystallizer is electromagnetically stirred to be 500mm below the liquid level of the steel, the current intensity is 350A, and the frequency is 1 Hz; the secondary cooling electromagnetic stirring is positioned 8000mm below the liquid level of the steel, the current intensity is 1000A, and the frequency is 8 Hz. Referring to fig. 1, the average value of the carbon content of 16 points at the position of frame type segregation 1 is taken to calculate the segregation index, and the carbon segregation index is reduced from 1.10 to 1.04 by adopting the parameter of the patent.
Example 3
A method for improving frame segregation 1 of a bloom continuous casting blank adopts a continuous casting machine to carry out continuous casting production:
wherein the carbon content of the steel is 0.40 percent (mass percentage content of C), the width of the continuous casting blank 2 is 480mm, the thickness is 320mm, the drawing speed is 0.51m/min, and the specific water content of the secondary cooling area is 0.25L/kg; the crystallizer is electromagnetically stirred to be 500mm below the liquid level of the steel, the current intensity is 250A, and the frequency is 2 Hz; the secondary cooling electromagnetic stirring is positioned 6000mm below the liquid level of the steel, the current intensity is 750A, and the frequency is 6 Hz. Referring to fig. 1, the average value of the carbon content of 16 points at the frame-type segregation position is taken to calculate the segregation index, and the carbon segregation 1 index is reduced from 1.08 to 1.03 by adopting the parameter of the patent.
Claims (1)
1. A method for improving the frame segregation of a bloom continuous casting billet is characterized by comprising the following steps: the method comprises the steps of adopting a continuous casting machine to carry out continuous casting production, wherein the section size of a casting blank of the continuous casting machine is 400-500mm in width and 400-400 mm in thickness; wherein the drawing speed of the continuous casting billet is 0.45-0.60 m/min; the specific water amount of the secondary cooling area is 0.20-0.30L/kg; the electromagnetic stirring current intensity of the crystallizer is 150-350A, the frequency is 1.0-2.5Hz, and the electromagnetic stirring of the crystallizer is arranged 500mm below the molten steel surface; the current intensity of the secondary cooling electromagnetic stirring is 500-1000A, the frequency is 5-8Hz, and the secondary cooling electromagnetic stirring is arranged below the surface of the molten steel by 5000-8000 mm.
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| CN201910299087.XA CN110000355B (en) | 2019-04-15 | 2019-04-15 | Method for improving frame segregation of bloom continuous casting billet |
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| CN201910299087.XA CN110000355B (en) | 2019-04-15 | 2019-04-15 | Method for improving frame segregation of bloom continuous casting billet |
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| CN110000355B true CN110000355B (en) | 2020-12-18 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110303125A (en) * | 2019-07-22 | 2019-10-08 | 攀钢集团攀枝花钢铁研究院有限公司 | Bloom Properties of Heavy Rail Steel homogenieity cooperates with lifting control method with compactness |
| CN110508763A (en) * | 2019-07-22 | 2019-11-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Large section Properties of Heavy Rail Steel microsegregation control method |
| CN110280733A (en) * | 2019-07-22 | 2019-09-27 | 攀钢集团攀枝花钢铁研究院有限公司 | Large section heavy rail rail head region homogenieity lifting control method |
| CN110508770A (en) * | 2019-07-22 | 2019-11-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Bloom Properties of Heavy Rail Steel microsegregation control method |
| CN110216252A (en) * | 2019-07-22 | 2019-09-10 | 攀钢集团攀枝花钢铁研究院有限公司 | Bloom heavy rail rail head region homogenieity method for improving |
| CN110216254A (en) * | 2019-07-22 | 2019-09-10 | 攀钢集团攀枝花钢铁研究院有限公司 | Properties of Heavy Rail Steel homogenieity improves control method |
| CN110280732A (en) * | 2019-07-22 | 2019-09-27 | 攀钢集团攀枝花钢铁研究院有限公司 | Large section Properties of Heavy Rail Steel homogenieity cooperates with lifting control method with compactness |
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| CN102310178A (en) * | 2011-07-08 | 2012-01-11 | 南阳汉冶特钢有限公司 | Method for solving center segregation of casting blank |
| CN102672130B (en) * | 2012-05-30 | 2013-10-16 | 东北大学 | Method for reducing Cr and Mo steel mill bar frame-shaped segregation |
| CN104308111B (en) * | 2014-11-19 | 2016-05-18 | 河北工程大学 | Reduce the method for bearing steel wire rod 1/2R place's gross segregation |
| CN106312000A (en) * | 2016-10-12 | 2017-01-11 | 中原特钢股份有限公司 | 18CrNiMo7-6 round billet continuous casting method for vertical type continuous casting production gear steel |
| CN109079114B (en) * | 2018-08-27 | 2021-01-26 | 南京钢铁股份有限公司 | Method for producing wear-resistant steel by adopting electromagnetic stirring in slab secondary cooling zone |
| CN109518076A (en) * | 2018-11-08 | 2019-03-26 | 邢台钢铁有限责任公司 | A kind of engine cranking motor axle-steel wire rod and its production method |
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